1. Field of Invention
This invention relates to abdominal exercise devices, specifically to an improved device for isolating and contracting the rectus abdominis while simultaneously elevating and supporting the head during abdominal exercising so as to prevent neck fatique or strain prior to abdominal muscular exhaustion.
2. Description of the Prior Art
Health club facilities commonly include "sit-up board" devices for isolating the abdominal muscles. Such devices to present date utilize a declining rigid horizontal board with apparatus for securing the feet.
Originally the boards were the only devices available for trunk flexion movements. The user is instructed to lie supine on the board with the feet secured and the hands interlocked behind the head. The movement consists of curling the trunk into a concave position as it is raised into a "sit up" position. Due to gravity, the head is supported by clasping the hands behind the head to aid in preventing neck fatigue.
With the help of medical science and the study of anatomy and physiology, it is known that the primary muscles used for hip flexion are the iliopsoas muscles or more commonly called "hip flexors". Because these muscles originate on the lumbar vertebrae and insert on the femurs (or thighs), many people experience lower back pain due to anterior pelvic tilting during such movements.
Several types of abdominal exercise devices have been developed to prevent pulling on the lower back vertebrae. One such device includes a molded plastic chair contoured to fit the natural curvature of the coccyx, sacral and lumbar vertebrae. The bottom of this chair has a curved "rocker arm" to make sitting up more comfortable on the user's "tail bone". The lumbosacral curvature provides added support to help raise the lower trunk of the user from a horizontal to vertical position during movement.
Another device utilizes a concave horizontal padded board for the user to lie supine. The intended purpose is to prevent the pelvis from tilting anteriorly during hip flexion movements. This device keeps the thoracic vertebrae in a concave position, thus not allowing the rib cage to elevate and thereby not permitting the rectus abdominus to lengthen as anatomically intended.
One other device incorporates a rope and pulley system. The pulley is mounted on a door knob or the like with the rope consisting of handles for the hands on one end and ankle harnesses for the feet. By lying on one's back with the head toward the pulley, the arms are pushed down from above the head to the hips. The rope then pulls the feet and legs over the chest to provide some tightening of the abdominal muscles. Like the previous device, the head remains on the ground so as not to allow the rib cage to depress, thereby not adequately shortening the rectus abdominus muscles.
Several machines have been developed that allow the user to begin in either a vertical or slightly inclined position. One machine provides a strap that is placed over the shoulders and held in the hands. After securing the feet to the floor, the trunk is then flexed forward with the head drawn toward the knees. An adjustable weight stack connected to a cable and pulley system provides negative resistance to pull the trunk back into the original inclined or vertical position. The primary muscles used for this movement are the "hip flexors" resulting in the rectus abdominus not being fully isolated.
Another weight machine is constructed so that the user is seated in a vertical position. With knees bent and feet secured by roller pads, the user then grips with the hands two handles located beside the head or slightly higher. Then by flexing the upper and lower trunk into a concave position, the user receives some resistance on the upper and lower portions of the rectus abdominus. This device is somewhat effective in isolating the rectus abdominus; however, it is very expensivcce to manufacture and difficult to transport due to its bulk and weight.
All of the known exercise devices suffer from one or more of the following disadvantages:
(a) The manufactuing of many prior art machines requires expensive production facilities that include welding and painting departsments. Also, the weight of each machine requires that the machines must be shipped on expensive trucking carriers instead of UPS or the like. The price of such machines can run into thousands of dollars, and the weight of such machines does not allow easy portable movement. Many of these machines cannot isolate the rectus abdominus without bringing the "hip flexors" into play. PA1 (b) The molded contoured chair device uses the "hip flexors" primarily without support of the cervical and head regions of the body. PA1 (c) The padded contoured horizontal board keeps the thoracic vertebrae in a concave position, thus not allowing the rib cage to elevate, thereby not permitting the rectus abdominus to lengthen as anatomically intended. PA1 (d) The rope and pulley device does not raise the head or cause the rib cage to depress, thereby not adequately shortening the rectus abdominus muscles. PA1 (e) The declined "sit-up" slant board device primarily results in hip flexion and does not give support to the vertebral column. Owing to gravity, the neck strain can only be relieved by clasping the hands behind the head during the "sit-up" or forward flexion movements.
Accordingly, a need has arisen for abdominal exercise device which provides support for the head and neck regions of the body, isolates the rectus abdominus, is simple in construction, lightweight, portable, adjustable and inexpensive to manufacture. The new and improved abdominal exercise device of the present invention meets this need.